2.8: How to enable Eevee on a Macbook pro?
It's not something you have to enable, EEVEE is just here and you have to chose it as your current render engine, just like before.

Go in the properties editor, you'll find a drop-down menu for choosing your render engine at the very top of the render tab :



EDIT: As the OP is already in rendered view in EEVEE and without materials, then it looks like a bug.